Project Summary The T32 Pathophysiology of Human Blood Cells, now in its 37th year of funding, is seeking renewal to continue a long-standing focus on training physician-scientists in pediatric Hematology/Oncology. The object of the training program is to provide PhD and PhD-post-doctoral level research experiences and scholarly research training in Hematology/Oncology, so as to render trainees independent investigators making substantive contributions to biomedical research, both basic and translational. The program has continued to grow in this last cycle with the appointments of Drs. Stuart Orkin as the Training Grant Co-Director and Scott Armstrong as the Accreditation Council for Graduate Medical Education (ACGME) Fellowship Program Director. In addition to maintaining the program's strengths in stem cell biology, platelets/ thrombosis, neutrophil biology/innate immunity, red cell biology/hemoglobin expression and an overall emphasis in translational research, we have expanded our efforts in areas of gene therapy and stem cell transplant. In addition, programs are in place to target women in undergraduate science classes and MD/PhD students at Harvard Medical School/MIT to enhance the future pipeline of trainees coming to this T32. The 60+ mentoring faculty on this training grant include outstanding scientists many with exemplary publication and training records. In spite of pressures on the NIH budget, research funds to the Division currently total $57.2 M in direct costs per year including 120 NIH grants. The total support to the mentoring faculty is $78,411,173 in direct costs for the current year. The training faculty is highly collaborative, and Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Stem Cell Institute, Harvard, Harvard Catalyst (CTSA) and MIT academic environments provide stellar opportunities for formal coursework and for a myriad of scientific seminars and lectures. Of those applying for positions on this T32, 5% are accepted. Of those accepted in the last 15 years, 15% were underrepresented minorities (URM) and 65% were women. There are formal processes in place for regular trainee and faculty feedback. Success of trainees as judged by success in obtaining NIH training grants and independent faculty positions is outstanding and nearly 100% of entering fellows remain in hematology/ oncology in scientific careers. Indeed, graduates of this training program now represent leaders in the field with significant numbers serving in academic or pharmaceutical/ biotech leadership positions. This success continues in the latest funded cycle. Of the 51 MD and MD/PhD trainees who have trained here within the past 15 years, 36 (71%) have obtained career awards and/or prestigious fellowships, including 18 K awards (1 K07, 1 K23, and 16 K08's; plus 2 funded on a K12) and 19 private fellowships (11 K award holders also obtained private fellowships). We are requesting renewal with funding to support 11 training slots in the next funding period.